Furnace more particularly for drying fuel



4 May 22, 1928. 1,670,606

E. W. BOWEN FURNACE MORE PARTICULARLY FOR DRYING FUEL Filed p 1927 2 Sheets-Sheet 1 May 22, 1928.

- E. W. BOWEN FURNACE MORE PARTICULARLY FOR DRYING FUEL 2 Sheets-Sheet 2 Filed Sept. .26, 1927 N .0 .1 T a .d N

Patented May 22, 1 .928.

stars rarest FURNACE MORE PARTICULARLY FOR DRYING FUEL.

Application filed September 26, 1927, Serial No. 222,058, and in Great Britain September 9, 1926.

.ihis invention has reference to furnaces for drying and making materials at definitely regulated ten'iperatures and its primary object is to provide a continuously operating furnace which shall be especially suited to the drying and baking of briquettes, ovoids and the like of fuel compounded from materials such as anthracite duff and other carbonaceous materials mixed with a suitable wet binder. In the production of this fuel it is important that the temperature at which the drying and baking is effected should be carefully controlled as excessive heat might engender carbonizing ofthe material with detrimental results.

lVith the above and other objects in view, the invention comprises an elongated furnace chamber heated by a plurality of individually controlled gas burners, continuously operating means for conveying the material to bebaked through the length of the chamber, anda plurality of individually adjustable outlets or fiuesspaced along the length of the furnace, these latter and the burners enabling the temperatures encountered by the material under treatment to be regulated as required. A bafi'le or screen is located between the burners and the out lets and the material being treated is carried by a conveyor along a path just below said baffle. Pyrometers may be provided at various points in the furnace chamber to guide the operator in the adjustments required to control the temperature.

The invention is hereinafter more fully described with reference to the accompanying drawing in which Fig. 1 is a transverse section of a furnace constructed in accordance with my invention, with parts indicated diagrammatically and Fig. 2 is a partial cross section of a furnace with a modified baffle or screen.

Fig. 3 is a vertical longitudinal sectional view of the form of the furnace shown in Fig. 1, with parts broken away and in which the conveyor is diagrammatically shown.

In the form of construction illustrated in F ig.- 1 the improved furnace comprises an elongated chamber a with a series of valve controlled gas burners. b and a series of valve controlled outlets or flues 0 arranged at spaced intervals along its length. Between the burners b and outlets 0 there is arranged a horizontally extending baffle or screen d composed of sheets of tire clay or refractory material carried on cross bearers (not shown) which operates to reflect the heat downwards on to the material being treated. The products of combustion from the burners. pass vertically through small slots, spaces or openings between the sheets in the baffle or around the sides of the baffle to the crown of the furnace chamber with which the outlets communicate.

An endless conveyor 7 of chain or other suitable type has one run extending horizontally through this heated space between.

the burners b and the baflle d and this carries the material to be dried and baked, slowly through the length of the furnace. The briquetted material may conveniently be laid upon trays and loaded on to the conveyor at one end of the furnace and discharged froin the remote end of the furnace after being baked. 0

During the passage of the trays through the furnace the heat is reflected downwardly by the baflie orSscreend, so that the fuel under treatment is subjected to equal or substantially equal temperature from above and helow, als'o the "baffle protects the heating zone beneath it against sudden changes of temperature due to alteration of; draught or bars h of refractory material which may be chamfered at their lower edges to facilitate the entry of gases to the spaces therebetween.

With a certain fuel of the kind referred to it is necessary to perform the drying and baking operation at a temperature of about 650 F. and when dealing with this material in the improved furnace the burners and outlets are so regulated as to obtain an actual furnace temperature of about 700 F. at the charging end where the cold and moist material enters, the temperature falling progressively throughout the length of the furnace to an actual 500 F. at the outlet end, although the pyrometers will register about 650 F. throughout the whole length of the furnace. Thus as the material moves through the furnace and warms up, the temperature to which it is subjected gradually diminishes and all risk of overheating is thereby avoided. The pyrometers arranged at intervals along the heating Zone of the furnace enable the operator to observe the temperatures and to estimate such adjust-- ments of the burners and flues as may be desirable.

Though I have described my improved furnace as arranged and operated for the drying and baking of briquettes and ovoids of fuel, I would have it understood that it may also be applied to. other purposes where it is necessary to subject materials to heat at definite or carefully regulated temperatures.

In one constructional form according to the present invention which has proved very successful under test, the furnace is 99 feet in overall length and measures 98 feet between the inner faces of the end doors. The gas burners comprise concentrically arranged inner and outer slot-ted tubes for gas and air respectively, extending transversely of the furnace. These burners are twenty-five in number and are spaced at the following centres, measurements commencing and ending with reference to the outer faces of the furnace :1 6, 2, 2', 2, 2, a, L, 4, 4, a, 4., 4., 4', 4., 4', 4', a, a, 4, a, a, 4 6, 6, 6, 1 6.

The dimensions of the main chamber give a volume of 1,550 cu. ft. below the trays, 730 cu. ft. above the trays making a total of 2,280 cu. ft. The volume of the chamber above thebaflle is 690 cu. ft. leading from main chamber into expansion chamber have an area of 1,780 sq. ins. The total available flue area to atmosphere is The slots 420 sq. ins. of which about 50 per cent is in use. A certain undeterminate volume of products of combustion leave the main chamher at either end through the space occupied by the trays.

I claim 1. An improved furnace for drying fuel comprising an elongated chamber, a plural ity of individually adjustable gas burners spaced along the length of the chamber, a

plurality of individually adjustable burnt as outlets spaced along the length of the chamber, means for conveying continuously the material to be dried through the length of the chamber between the burners and outlets and a baffle composed of spaced sheets of refractory material located between the conveying means and the gas outlets.

2. An improved furnace for drying fuel comprising an elongated chamber, a plurality of individually adjustable gas burners spaced along the length of the chamber, a plurality of individually adjustable burnt gas outlets'spaced along the length of the chamber, means for conveying continuously the material to be dried through the length of the chamber between the burners and the outlets, and a baffle having a plurality of openings distributed throughout its length for thepassage of the burnt gases, said baflle being adapted to reflect the heat downwardly so that the material under treatment is subjected to equal or substantially equal temperatures from above and below.

In testimony whereof he has afliXed his signature.

ERNEST WINDSOR BOWEN. 

